Certain pharmacological characteristics of the release of pancreatic glucagon in response to stimulation of the splanchnic nerves.

1. The effect of alpha- and beta-adrenoceptor blockade on the release of pancreatic glucagon, in response to stimulation of the peripheral ends of the splanchnic nerves has been examined in adrenalectomized calves 3-5 weeks after birth. In addition, the effects of insulin, atropine and somatostatin on the glucagon response to splanchnic nerve stimulation have been assessed in adrenalectomized dogs. 2. In calves release of pancreatic glucagon in response to splanchnic nerve stimulation was not suppressed by phentolamine at a dose that effectively abolished alpha-adrenergic inhibition of insulin release, or by propranolol, at a dose that completely eliminated the chronotropic action of the cardiac sympathetic innervation. 3. In dogs release of pancreatic glucagon in response to splanchnic nerve stimulation was not suppressed by atropine (0.2 mg/kg) or somatostatin, at a dose that caused a steady fall in the concentration of gastrin in the circulating plasma (0.5 microgram-kg-1 min-1). Glucagon release was apparently potentiated by exogenous insulin (4.0 u./kg). 4. The results are discussed in relation to the findings of other workers and it is concluded that the precise mechanism whereby stimulation of the sympathetic innervation to the pancreas leads to secretion of glucagon merits more detailed investigation.